title: The in vitro secretome of Mycosphaerella fijiensis induces cell death in banana leaves.
abstract: The hemibiotrophic filamentous fungus Mycosphaerella fijiensis causes the banana foliar disease known as black Sigatoka, responsible for major worldwide losses in the banana fruit industry. In this work the in vitro secretome of M. fijiensis was characterized. Native and denaturant polyacrylamide gel protease assays showed the M. fijiensis secretome contains protease activity capable of degrading gelatin. Necrotic lesions on leaves were produced by application of the in vitro secretome to the surface of one black Sigatoka-resistant banana wild species, one susceptible cultivar and the non-host plant Carica papaya. To distinguish if necrosis by the secretome is produced by phytotoxins or proteins, the latter ones were precipitated with ammonium sulfate and applied in native or denatured forms onto leaves of the same three plant species. Proteins applied in both preparations were able to produce necrotic lesions. Application of Pronase, a commercial bacterial protease suggested that the necrosis was, at least in part, caused by protease activity from the M. fijiensis secretome. The ability to cause necrotic lesions between M. fijiensis secreted- and ammonium sulfate-precipitated proteins, and purified lipophilic or hydrophilic phytotoxins, was compared. The results suggested that leaf necrosis arises from the combined action of non-host specific hydrolytic activities from the secreted proteins and the action of phytotoxins. This is the first characterization of the M. fijiensis protein secretome produced in vitro but, more importantly, it is also the first time the M. fijiensis secretome has been shown to contain virulence factors capable of causing necrosis to its natural host.
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán AC, Calle 43, No 130, Colonia Chuburná de Hidalgo, 97200 Mérida, Yucatán, Mexico.
authors.forename: José
authors.initials: J
authors.lastname: Chuc-Uc
authors.forename: Ligia
authors.initials: L
authors.lastname: Brito-Argáez
authors.forename: Blondy
authors.initials: B
authors.lastname: Canto-Canché
authors.forename: Miguel
authors.initials: M
authors.lastname: Tzec-Simá
authors.forename: Cecilia
authors.initials: C
authors.lastname: Rodríguez-García
authors.forename: Leticia
authors.initials: L
authors.lastname: Peraza-Echeverría
authors.forename: Santy
authors.initials: S
authors.lastname: Peraza-Echeverría
authors.forename: Andrew
authors.initials: A
authors.lastname: James-Kay
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Cruz-Cruz
authors.forename: Luis Manuel
authors.initials: LM
authors.lastname: Peña-Rodríguez
authors.forename: Ignacio
authors.initials: I
authors.lastname: Islas-Flores
mesh_terms: D001203:Ascomycota / Q000472:pathogenicity*; D029441:Carica / Q000187:drug effects / Q000382:microbiology; D016923:Cell Death / Q000187:drug effects*; D010450:Endopeptidases / Q000494:pharmacology*; D005656:Fungal Proteins / Q000494:pharmacology*; D054884:Host-Pathogen Interactions; D006868:Hydrolysis; D028521:Musa / Q000145:classification / Q000187:drug effects / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000187:drug effects / Q000382:microbiology*; D013045:Species Specificity; D037521:Virulence Factors / Q000494:pharmacology
chemical_list: D005656:Fungal Proteins; D037521:Virulence Factors; D010450:Endopeptidases